Why Guys Get Grouchier As They Age

Is he acting like Oscar the Grouch again? Turns out, the aging process might be to blame.

Introducing "grumpy old man complex", where as men age, testosterone levels drop and they turn grumpy. Sounds fun, huh?

“Testosterone is a hormone that grows muscles, reduces fat in the body, affects energy and improves sexual desire," Dr. Ridwan Shabsigh, head of the International Society of Men’s Health and a urologist in New York City told MSNBC. "However, it also has neural-psycho effects. And in some men we encounter in our practice, those affects can be mostly visible: low mood and irritability."

Additionally, metabolic and kidney diseases, such as diabetes, which are more popular with old age, are known to cause extremely low testosterone.

Though hormone drops aren't the only aging factor triggering irritability — it's their concerns too. According to Carol Wyer, author of the upcoming book "How Not To Murder Your Grumpy", "While women often chat with their friends about the aging process, men are more likely to supress their worries."

These grumpy outbursts typically hit around age 60 — so technically there's no reason for him to be yelling at the neighbor's dog until then.